Why does God let man suffer?

This question is even more insistent when we see good people suffering, people who are necessary for others, and on the other hand, various criminals, mafiosi, doing well. They are healthy; they live to a ripe old age, and so on. Many will say God is unjust. But we know that God is, and He has all eternity to show that He is just. But the truth is that we cannot always explain why even good people have to suffer. We have to accept the fact that God has a purpose with this. But we know that not all good people have to suffer, and not all bad people do well. It goes from case to case. But one thing is certain, everything that occurs to us in our lives has a significance, and we should learn to respond to it, to ask what God wants to say to us with this event. But we must be careful that our reactions to suffering are not adverse. As it was with the Jews. They were convinced, if someone was sick or suffering, they must be a sinner. However, if he did not outwardly appear to be a sinner, the Jews were convinced that he was a secret sinner. In a word, the Jews considered sickness suffering punishment for sin. On the other hand, in quotation marks, we cannot blame God for suffering we have caused ourselves. I know a man who was driving a car over 200 kilometers. He had a crash. He survived, but became paralyzed, became an invalid. His family, however, blamed the Lord God; how could he let this happen. I am not saying anything new if I say, many sufferings and illnesses are our own fault, they have their natural cause, and it is not right to blame the Lord God for it.